Tobacco-smoke filters

ABSTRACT

The invention concerns a multicomponent filter for tobaccosmoking articles, such as cigarettes. A three-component filter has at least an absorbent filter section, an aqueous humidifying means and a poorly absorbent section. The humidifying means is to enhance the filtering action and/or serve as a flavorant or flavor-enhancing agent.

United States Patent Horsewell et al.

[151 3,635,226 1451 Jan. 18,1972

1541 TOBACCO-SMOKE FILTERS [72] Inventors: Henry George HorsewellrThomas William Charles Tolman, both of London, England [73] Assignee:British-American Tobacco Company Limited, London, England [22] Filed:June 16, I969 [21] Appl. No.: 833,389

[52] U.S.Cl ..l31/266,131/10.1,131/267, 131/269 [51] Int. Cl ..A24b15/02, A24d 01/06 [58] FieldolSearch ..l3l/9, 101,261,261 A, 10.7,131/267 [56] References Cited UNITED STATES PATENTS 3,061,479 10/1962Merritt ..13l/l7 2,808,057 10/1957 Jaksch..... 131/10 1 2,863,46112/1958 Frost.... .....131/l01 3,250,280 5/1966 Hu 131/10.1 X 3,251,3655/1966 Keith et a1. ..l3l/10.7 3,340,879 9/1967 Horsewell et a1...131/267 3,366,121 1/1968 Carty ..l3l/l0.l 3,390,686 7/1968 lrby et al..l3 III 0.1

FOREIGN PATENTS OR APPLICATIONS 542,106 4/1956 Italy .Q ..l31/262 A531,509 8/1955 Italy ..l3l/265 OTHER PUBLICATIONS Shmuk, A. A. (1961)The Chemistry and Technology of Tobacco. Available from Off. of Tech.Services, US. Dept. Comm. PST No. 96. pg. 499.

Primary Examiner-Aldrich F. Medbery Assistant Examiner-G. M. YahwakAttorney-- Kane, Dalsimer, Kane, Sullivan and Kurucz [57] ABSTRACT Theinvention concerns a multicomponent filter for tobaccosmoking articles,such as cigarettes. A. threewomponent filter has at least an absorbentfilter section, an aqueous humiditying means and a poorly absorbentsection. The humidifying means is to enhance the filtering action and/orserve as a flavorant or flavor-enhancing agent.

5 Claims, 5 Drawing Figures TOBACCO-SMOKE FILTERS This inventionconcerns improvements relating to tobaccosmoke filters, particularly butnot exclusively such for cigarettes, cigars and like smoking articles.

According to the invention, a three component tobaccosmoke filters withtwo or more filter sections comprise an absorbent section, an aqueoushumidifying means and a poorly absorbent section. The humidifying meansmay comprise water, or other aqueous medium, which will, during smoking,serve to enhance the action of a filter material, especially that of theabsorbent section, with which it is used, or serve as a flavorant orflavor-enhancing agent. it may be a solution or suspension of such areagent or flavorant.

The absorbent section preferably comprises a highly waterabsorbentmaterial, such as paper or paper wadding. The poorly absorbent sectionpreferably comprises a substantially nonabsorbent fibrous or filamentarymaterial, such as cellulose acetate, or a substantially nonabsorbentfoam material.

in one advantageous form, the filter may consist of only two sections,the humidifying means being deposited upon or otherwise carried by thematerial of the absorbent filter section. The humidifying meanscomprises a highly hygroscopic substance such as lithium chloridemagnesium chloride or giycerine as well as water or other aqueous mediumso that the absorbent section maintains itself in a wetted condition,

'whereby good filtration properties are ensured.

in another advantageous form, comprising three sections, the humidifyingmeans is contained in a separate section, preferably located between thehighly and relatively poorly absorbent sections. In this form of filter,the humidifying means, i.e., water or an aqueous solution of afiltrationenhancing or flavor-enhancing substance, may be contained inliquid form in an impermeable rupturable enclosure. Thus the aforesaidsection may consist of or contain an impermeable capsule or capsules, orgroups of capsules, which contain the humidifying means in liquid formand which are rupturable by fingerpressure exerted on the said section.This section may also comprise an absorbent material, such as paper orpaper wadding, which may surround or embed the capsule or capsules orinto which the liquid humidifying means may be absorbed.

With this form of filter, rupture of the capsule or capsules releasesthe liquid humidifying means which is absorbed preferentially by thematerial of the absorbent section. Even plain water thus added toordinary tobacco-smoke filter paper enhances the selective filtrationproperties of the paper for the volatile constituents of the vapor phaseof the smoke.

Particularly effective filtration can be achieved if the material of theabsorbent section has been treated with an additive, such aspolyethylene imine and/or zinc acetate, having a filtration-enhancingaction. Such an additive may altematively or additionally beincorporated in the liquid humidifying means or applied to absorbentmaterial of the aforesaid separate section. if filter paper has beentreated with such an additive having a known selective effect upon thevolatile constituents of the smoke, the application of water to thepaper produces a very marked improvement in the selective effect. Aflavor-enhancing substance may be similarly applied in any of theaforesaid ways.

The quantity of water or aqueous medium provided in such a capsule orcapsules will depend upon the requirements for the particular smokingarticle. in the case of a typical conventional cigarette, it has beenfound that about 50 mg. will provide an excellent effect. A highercontent of, say, 100 or 150- mg. is of advantage with respect to theremoval of more volatile constituents only. For practical purposes, acapacity range of from to 500 mg. is preferred.

With filters of each of the forms set forth above, the poorly absorbentsection forms a mouth end section of the filter and the absorbentsection is located at the other end of the filter where it will beadjacent to the tobacco of the smoking article.

Examples illustrating the preparation of such filters will now be morefully described, together with experimentally determined filtrationresults obtained from the filters:

EXAMPLE 1 Absorbent filter sections were prepared by spraying a solutionof lithium chloride onto tobacco-smoke filtering paper of the type knownas Myria to give a weight of lithium chloride of 40 percent based on theweight of the original paper. The treated paper was allowed to come toequilibrium in ambient humidity conditions and was formed into filterrods which were cut into sections of i5 mm. length. The sections werefound by analysis to contain 39.4 percent by weight of lithium chlorideand 38 percent water. 7

These sections were assembled into filter-tipped cigarettes using at themouth-end of each filter a 15 mm. long nonabsorbent section ofcellulose-acetate filter of filament denier 8, and tow denier 48,000,the paper section being adjacent to the tobacco rod. The cigarettes weresmoke using a smoking engine which provided one puff per minute of 2seconds duration and 35 ml. volume. The proportions of tobacco-smokeconstituents removed by the filter are shown in table 1.

EXAMPLE ll TABLE I Constituent removed (percent) Hydro- Baked Nico- Phe-Aldegen Filter tar tine nois hydes cyanide EXAMPLE lll Filter sectionswere prepared 'as in example i except that magnesium chloride was usedin place of lithium chloride. After equilibration, analysis showed thatthe sections contained 40 percent by weight of magnesium chloride and 45percent of water. Filter-tipped cigarettes were prepared and smoked asin example I. The proportions of smoke constituents removed are shown intable ll.

EXAMPLE iV Filter sections were prepared as in example ll except thatmagnesium chloride was used in place of lithium chloride. Afterequilibration, analysis showed that the sections contained l0 percent byweight of polyethylene imine, 40 percent of magnesium chloride and 45percent of water. Filter-tipped cigarettes were prepared and smoked asin example l. The proportions of smoke constituents removed are shown intable Ii.

TABLE II Constituent removed (percent) Hy ro Baked Nico- Phe- AldegenFilter tar tine nols hydes cyanide Example III..." 12 13 15 10 10 IV. 4142 30 49 67 EXAMPLEV Filter tips were prepared consisting of threesections, an end section of 15 mm. length consisting of tobacco-smokefiltering paper of the type known as Myria," a center section comprisinga sealed capsule containing 50 mg. of water, consisting of a 7 mm.length of plasticized polyvinyl chloride tubing of 6.7 i: 0.1 mm.outside diameter sealed at each end with a friable rosin-based resin,i.e., that supplied under the name Pioneer E 15 resin by Frederick BoehmLtd., and an end section consisting of a 15 mm. length of celluloseacetate filter of filament denier 8 and total tow denier 48,000.

EXAMPLE VI Filters were prepared as in example V except that the sealedcapsule contained I mg. of water.

EXAMPLE VII TABLE III Constituent Removed Weight of water per filter(mg.)

Baked Tar 42 45 40 35 Nicotine 42 4| 40 34 Phenols 48 48 48 48 Acids 4964 64 64 Aldehydes less than 10 l l l6 2| Hydrogen Cyanide 22 42 43 44Hydrogen Sulphide less than l0 l2 I7 25 EXAMPLES VIII-.-X

Filters, including comparison filters, were prepared as for examplesV-VII, except that the paper section was pretreated to contain I0percent by weight of polyethylene imine calculated on the originalweight of the paper. Cigarettes were prepared and smoked as describedfor examples V to VII and the proportions removed, for the more volatileconstituents of the smoke, are given in table lV.

TABLE IV Constituent Removed Weight of water per filter (mg.)

Aldehydes l5 70 82 82 Hydrogen Cyanide 65 83 86 89 Hydrogen Sulphide I752 76 90 Tables III and IV suggest that, for the less volatilecomponents of the smoke, e.g., tar; nicotine, phenols and acids, only atrace of water, e.g., 50 mg., produces a maximum effect which is notimproved by further quantities of water. For more volatile components,aldehydes and hydrogen sulphide, and to a lesser extent hydrogencyanide, increasing water content gives increasing removal, especiallywhen the additive, polyethylene imine, is present as well as the water.

Apart from polyethylene imine, other filtration-enhancing additives,which may be added to the paper section or incorporated into the watercontained in the frangible or rupturable section, are zinc acetate,sodium carbonate, trisodium orthophosphate. Suitably the concentrationshould be up to 15 percent by weight of the paper section and ispreferably from 5-10 percent.

By way of further example, comparison of smoke produced by smokingcigarettes through similar filters including a paper section treatedwith 5 percent by weight of zinc acetate, with and without the additionof I00 mg. of water gave the following results.

For the three-section form of filter, the capsules may be of anyconvenient shape, for example cylindrical, spherical or ovoid, and theliquid may be encapsulated in various way, as hereinafter described.

Examples of filter assemblies in accordance with the invention areillustrated in the accompanying drawing, in which:

- FIG. 1 is a perspective view of a two-section cigarette filter,

FIG. 2 a similar view of a three-section cigarette filter,

FIGS. 3 and 3a are perspective views of forms of capsule for use in suchfilters, and

FIG. 4 an exploded view of another form of capsule.

FIG. 1 illustrates a cigarette having a filter which comprises anabsorbent section 1 between the wrapped tobacco rod 2 and a nonabsorbentsection 3. The filter can be wrapped in a liquid impermeable material 4,for example cork tipping or white paper suitably treated to render itimpermeable. The sections 1 and 3 of this filter may be constituted inthe manner described in any of examples I to IVv Alternatively, lithiumchloride or other humidifying means could be dispersed in the section 1in a plastic or wax material.

In FIG. 2, a section 5 containing a liquid humidifying means is locatedbetween a nonabsorbent section 3 and an absorbent section 6. Thesections 3, 5 and 6 of this filter may be constituted in the mannerdescribed in any of examplesV to X. One suitable form of cylindricalcapsule which can be used as the section 5 is shown in FIG. 3. It isproduced from a thinwalled flexible or semiflexible tube 7 sealed atboth ends 8 by a rupturable resin as described under example V. The tube7 is suitably of a plastics material, such as polyvinyl chloride,polystyrene, polyethylene or polypropylene. It may be of the sameexternal diameter as the other filter sections and may have smooth orfluted walls.

End sealing may alternatively be effected by a frangible wax compositionsuch as a mixture of paraffin-type waxes blended with polyethylene,suitably the composition of this type supplied by Campbell TechnicalWaxes Ltd.

Another form of end seal may be provided by a rupturable film such asthe clear adhesive cellulose-type tape sold under the Trade Mark Scotchby Minnesota and Mining Manufacturers Ltd. Seals may consist ofcombinations of materials, for example a flexible plastics cap with acentral aperture closed by a frangible resin or wax. Only one end mayhave a readily frangible cap, the other end being closed in some othermanner.

A cylindrical capsule of the same appearance as that of FIG. 3 mayalternatively be made wholly of wax.

A spherical all wax capsule, 7 FIG. 3a, is a practically advantageousform of capsule.

A wax capsule can be produced from wax by a sintering process, whichallows of the production of a cup of accurately reproducible dimensions.The cup can readily be sealed by a wax/polyethylene composition.

Alternatively, a capsule may comprise a structure with water-resistantgelatin walls with contents which comprise at least percent by weight ofglycerine in an aqueous medium.

As a further alternative, the aqueous medium may be contained in thecells of a frangible foam or cellular material. A suitable foam may beprepared by stirring together a mixture of one part by weight of moltenparaffin wax and two parts of water. On cooling slowly, the stable foamforms a soft gel and can be moulded to form units of filter roddimensions which can then be cut to fonn filter sections. Conventionalpolymers of low-molecular weight, for instance low-molecular weightpolystyrene, may be used in place of the wax.

As illustrated in FIG. 4, cups formed from a thermoplastic plasticsmaterial in sheet form, such as polyethylene or polystyrene, may also beused as capsules. A cap 9 of generally cylindrical shape is closed,after filling, with a cap 10 of plastics material which is sealed to thecup by wax or resin, as previously described.

The encapsulated liquid may, if desired, be absorbed intosmoke-filtering material which is also enclosed in the capsules.

We claim:

1. A tobacco-smoke filter assembly comprising: a tubular wrapper withinwhich is disposed in sequential axial alignment, a filter plug ofcellulose acetate abutting the mouth end of said assembly and a filterplug comprising a water-absorbent filter material having depositedthereon from about 5 to 15 percent by weight based on the absorbentmaterial of a polyalkyleneimine and a compound selected from the groupconsisting of lithium chloride, magnesium chloride and mixtures thereof,said filter assembly having from about 10 to I50 milligrams of waterabsorbed thereon.

2. The invention in accordance with claim 1, wherein the water-absorbentfilter material is paper.

3. A tobacco-smoke filter assembly comprising: a tubular wrapper withinwhich is disposed in sequential axial alignment, a filter plug ofcellulose acetate abutting the mouth end of said assembly and a filterplug comprising a water-absorbent filter material having depositedthereon from about 5 to 15 percent by weight based on the absorbentmaterial of a polyalkyleneimine, said filter assembly having from about50 to milligrams of water associated therewith.

4.. A tobacco smoke filter assembly comprising: a tubular wrapper withinwhich is disposed in sequential axial alignment, a filter plug ofcellulose acetate abutting the mouth end of said assembly, a frangiblecapsule containing from about 50 to 150 milligrams of water and a filterplug of water absorbent material having deposited thereon. apolyalkyleneimine present in amounts from about 5 to 1.5 percent byweight of absorbent material.

5. The invention in accordance with claim 3 wherein th water-absorbentfilter material is paper.

2. The invention in accordance with claim 1, wherein the water-absorbentfilter material is paper.
 3. A tobacco-smoke filter assembly comprising:a tubular wrapper within which is disposed in sequential axialalignment, a filter plug of cellulose acetate abutting the mouth end ofsaid assembly and a filter plug comprising a water-absorbent filtermaterial having deposited thereon from about 5 to 15 percent by weightbased on the absorbent material of a polyalkyleneimine, said filterassembly having from about 50 to 150 milligrams of water associatedtherewith.
 4. A tobacco smoke filter assembly comprising: a tubularwrapper within which is disposed in sequential axial alignment, a filterplug of cellulose acetate abutting the mouth end of said assembly, afrangible capsule containing from about 50 to 150 milligrams of waterand a filter plug of water absorbent material having deposited thereon apolyalkyleneimine present in amounts from about 5 to 15 percent byweight of absorbent material.
 5. The invention in accordance with claim3 wherein the water-absorbent filter material is paper.